1. Field of the Invention
The present invention relates to a polymerization catalyst component, method of making such a component, to a catalyst system made thererom, to a method of making such a catalyst system, to polymerization with such a catalyst and to polymer and products made therefrom. In another aspect the present invention relates to olefin polymerization catalyst components, to a method of making such a component, to a catalyst system made thererom, to a method of making such a catalyst system, to polymerization with such a catalyst and to polymer and products made therefrom. In even another aspect, the present invention relates to a polymerization catalyst component for making polyethylene, to a method of making such a component, to a catalyst system made thererom, to a method of making such a catalyst system, to polymerization with such a catalyst and to polymer and products made therefrom. In still another aspect, the present invention relates to a polymerization catalyst component useful for making propylene blends comprising iso- and syndio-tactic polypropylene, to a method of making such a component, to a catalyst system made thererom, to a method of making such a catalyst system, to polymerization with such a catalyst, and to polymer and products made therefrom.
2. Description of the Related Art
As is well known, various processes and catalysts exist for the production of polypropylene.
For example, the traditional Ziegler-Natta catalyst systems utilize a transition metal compound cocatalyzed by an aluminum alkyl.
xe2x80x9cMetallocenexe2x80x9d catalysts for olefin polymerization, comprising a metallocene and an aluminum alkyl component were first proposed in the 1950s. In a metallocene catalyst system, the transition metal compound has two or more cyclopentadienyl ring ligands. Accordingly, titanocenes, zirconocenes and hafnocenes have all been utilized as the transition metal component in such xe2x80x9cmetallocenexe2x80x9d containing catalyst systems for the productions of polyolefins. When such metallocenes are cocatalyzed with an aluminum alkyl, as is the case with the traditional Ziegler-Natta catalyst system, the catalytic activity of such metallocene catalyst system is generally too low to be of any commercial interest.
It has since become known that such metallocenes may be cocatalyzed with an alumoxane, rather than an aluminum alkyl, to provide a metallocene catalyst system of high activity for the production of polyolefins.
Polypropylene has long been known to exist in several forms. In isotactic propylene (iPP), the methyl groups are attached to the tertiary carbon atoms of successive monomeric units on the same side of a hypothetical plane through the polymer chain. Syndiotactic polypropylene (sPP) has the methyl groups attached on alternating sides of the polymer chain.
U.S. Pat. No. 4,939,202, issued Jul. 3, 1990 to Maletsky et al. discloses a barrier guard moisture-proof adhesive coating comprising isotactic and syndiotactic polypropylene. The amorphous polypropylene is said to be formed in minor amounts during the production of crystalline propylene using known sterospecific catalysts.
U.S. Pat. No. 5,124,404, issued Jun. 23, 1992 to Atwell et al. discloses the grafting or brominated monomeric units onto syndiotactic or isotactic polypropylene to form flame retardant polymer.
U.S. Pat. No. 5,269,807, issued Dec. 14, 1993 to Liu discloses a suture fabricated from a blend of comprising syndiotactic and isotactic polypropylene.
E.P. Patent Application No. 0 622 410 A1, published Nov. 2, 1994, discloses melt blending of syndiotactic polypropylene and isotactic polypropylene to form useful medical articles.
E.P. Patent Application No. 0 650 816 A1, published May 3, 1995, discloses injection molding blends of syndiotactic polypropylene and isotactic polypropylene. The blend is made by melt blending syndiotactic polypropylene and isotactic polypropylene.
E.P. Patent Application No. 0 615 818 A2, published May 3, 1995, discloses a method of forming a film by tubular film extrusion of a polypropylene resin composition comprising syndiotactic polypropylene and isotactic polypropylene. The blend is made by melt blending syndiotactic polypropylene and isotactic polypropylene.
U.S. Pat. No. 5,444,125, issued Aug. 22, 1995 to Tomita et al. discloses laminated olefin polymers obtained by introducing an amino group, into the terminal unsaturated isotactic or syndiotactic alpha-olefin polymer having an olefinic unsaturated bond at its terminus.
U.S. Pat. No. 5,455,305, issued Oct. 3, 1995 to Galambos discloses yarn made from blends of syndiotactic polypropylene and isotactic polypropylene.
U.S. Pat. No. 5,459,117, issued Oct. 17, 1995 to Ewen discloses double-conformationally locked, stereorigid catalysts for the preparation of tactiospecific polymers. Specifically, a double-conformationally locked metallocene, i.e., the chain-end is locked conformationally by two sterically different substituents at the distal ring carbon atoms of the cyclopentadienyl radical. The catalysts can be designed to impart any degree of tacticity to the resulting polymers by varying the substituents at the distal ring carbon atoms.
A wide range of properties from polyolefins, when produced by Ziegler-Natta catalyst systems, is generally obtained by introducing some amounts of various comonomers. The addition of a comonomer alters the thermal characteristics, i.e., decreasing melting temperature. Ethylene is a typical comonomer for polypropylene, with various weight percentages incorporated into polypropylene depending upon the application and manufacturing process.
According to one embodiment of the present invention there is provided a polyolefin metallocene catalyst component which can generally be described as having two different sterospecific sites, syndiospecific and isospecific. This metallocene catalyst component first includes a catalyst support. The catalyst system further includes two metallocene components, a stereorigid isospecific metallocene catalyst component and a stereorigid syndiospecific metallocene catalyst component, both of which are supported upon the support.
In a more specific embodiment of the catalyst component the stereorigid isospecific metallocene catalyst component is described by the formula:
Rxe2x80x3(CpR2C4R4)(CpRxe2x80x22C4Rxe2x80x24)MeQk
wherein (CpR2C4R4) and (CpRxe2x80x22C4Rxe2x80x24) are substituted indenyl rings; each R and Rxe2x80x2 is a hydrogen or a hydrocarbyl radical having 1-20 carbon atoms, each R being the same or different, each Rxe2x80x2 also being the same or different, one R and Rxe2x80x2 being a hydrocarbyl radical having 1-20 carbon atoms in a proximal position adjacent to the bridgehead carbon of the indenyl rings; Rxe2x80x3 is a structural bridge between the two indenyl rings imparting stereorigidity to the indenyl rings; Me is a transition metal; and each Q is a hydrocarbyl radical or is a halogen; and
the stereorigid syndiospecific metallocene catalyst component is described by the formula:
Rxe2x80x3(CpRn)(CpRxe2x80x2m)MeQk
wherein each Cp is a cyclopentadienyl or substituted cyclopentadienyl ring; Rn and Rxe2x80x2m are hydrocarbyl radicals having 1-20 carbon atoms, each Rn may be the same or different, and each Rxe2x80x2m also may be the same or different; Rxe2x80x3 is a structural bridge between the two Cp rings imparting stereorigidity to the Cp rings within the catalyst, and Rxe2x80x3 is preferably selected from the group consisting of an alkyl radical having 1-4 carbon atoms or a hydrocarbyl radical containing silicon, germanium, phosphorus, nitrogen, boron, or aluminum; Me is a group 4b, 5b, or 6b metal from the Periodic Table of Elements; each Q is a hydrocarbyl radical having 1-20 carbon atoms or is a halogen; 0≲k≲3; 0≲n≲4; and 1≲m≲4, and Rxe2x80x2m is selected such that (CpRxe2x80x2m) is a substantially different substituted ring other than (CpRn).
According to another embodiment of the present invention, there is provided a method of making the above described polyolefin metallocene catalyst component. The method generally includes contacting the two above described metallocene components, that is, the stereorigid isospecific metallocene catalyst component and the stereorigid syndiospecific metallocene catalyst component, with a support.
Accoring to even another embodiment of the present invention there is provided a catalyst system comprising the above described catalyst component and a cocatalyst or Lewis acid.
According to still another embodiment of the present invention, there is provided a method of making the above described catalyst system. The method includes contacting the polyolefin metallocene catalyst component with a cocatalyst or Lewis acid.
According to yet another embodiment of the present invention, there is provided a method for polymerizing of olefins with at least three carbon atoms. The process includes contacting olefins of at least three carbons with a catalyst system under polymerization conditions to form a blend of isotactic and syndiotactic polymer of high molecular weight and crystallinity, wherein the catalyst system is as described above.